High frequency module

ABSTRACT

A transmission filter in a high frequency module includes serial arm resonators electrically connected in series to a serial arm electrically connecting a shared terminal and a transmission terminal, parallel arm resonators each electrically connected in series to each of parallel arms electrically connecting the serial arm and a ground, a first inductor electrically connected between the ground and a connection end electrically connecting at least the two parallel arm resonators of the parallel arm resonators, and a second inductor electrically connected between the ground and one parallel arm resonator different from the at least two parallel arm resonators of the parallel arm resonators. The second inductor is electromagnetic field coupled to at least one of an antenna side matching element, a transmission side matching element, and a portion of the serial arm in the transmission filter. The first and second inductors obstruct electromagnetic field coupling therebetween.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2015-095948 filed on May 8, 2015 and is a ContinuationApplication of PCT Application No. PCT/JP2016/057913 filed on Mar. 14,2016. The entire contents of each application are hereby incorporatedherein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a high frequency module including atransmission filter and a reception filter.

2. Description of the Related Art

A mobile apparatus or the like for wireless communication includes atransmission filter and a reception filter. The transmission filterpasses only a component of a pass band of a transmission signal which isa high frequency signal, and attenuates components other than thecomponent of the pass band. The reception filter passes only a componentof a pass band of a reception signal received by an antenna, andattenuates components other than the component of the pass band (forexample, see International Publication No. 2015/019722).

A high frequency module disclosed in International Publication No.2015/019722 includes a transmission filter between a shared terminalelectrically connected to an antenna and a transmission terminal. Thehigh frequency module includes a reception filter between the sharedterminal and a reception terminal. The transmission filter includes aplurality of serial arm resonators electrically connected in series to aserial arm electrically connecting the shared terminal and thetransmission terminal. The transmission filter includes a plurality ofparallel arm resonators each electrically connected in series to each ofa plurality of parallel arms electrically connecting the serial arm anda ground.

Further, the high frequency module disclosed in InternationalPublication No. 2015/019722 includes an inductor electrically connectedbetween the ground and a connection end electrically connecting twoparallel arm resonators of the plurality of parallel arm resonators. Inthe high frequency module, inductive coupling is generated between theinductor and a matching inductor electrically connected to the sharedterminal. It is stated that, in the high frequency module disclosed inInternational Publication No. 2015/019722, isolation characteristicsbetween the transmission terminal and the reception terminal areimproved by an adjustment path defined by the inductive coupling.

Further, the high frequency module disclosed in InternationalPublication No. 2015/019722 includes, in addition to the inductorelectrically connected between the ground and the connection endelectrically connecting the two parallel arm resonators, an inductorelectrically connected between the ground and another parallel armresonator other than the above two parallel arm resonators. It is statedthat this inductor improves attenuation characteristics of thetransmission filter.

However, the high frequency module disclosed in InternationalPublication No. 2015/019722 does not take it into consideration toprovide both the improvement in isolation characteristics and theimprovement in harmonic attenuation characteristics of the transmissionfilter at the same time. In the high frequency module disclosed inInternational Publication No. 2015/019722, in the case where, forexample, the arrangement or the like of one of the inductors is adjustedin order to adjust the isolation characteristics, the harmonicattenuation characteristics of the transmission filter are affected insome case. In other words, in the high frequency module disclosed inInternational Publication No. 2015/019722, in the case where inductanceof the other one of the inductors is adjusted in order to adjust theharmonic attenuation characteristics of the transmission filter, theisolation characteristics are affected in some case. As such, with thehigh frequency module disclosed in International Publication No.2015/019722, it is difficult to provide, at the same time, theimprovement in isolation characteristics and the improvement in harmonicattenuation characteristics of the transmission filter.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide high frequencymodules that are excellent in isolation characteristics and alsoexcellent in harmonic attenuation characteristics of a transmissionfilter.

A high frequency module according to a preferred embodiment of thepresent invention includes a shared terminal electrically connected toan antenna, a transmission terminal, a reception terminal, atransmission filter electrically connected between the shared terminaland the transmission terminal, a reception filter electrically connectedbetween the shared terminal and the reception terminal, and an antennaside matching element electrically connected between the shared terminaland a connection portion of the transmission filter and the receptionfilter, or a transmission side matching element electrically connectedbetween the transmission terminal and the transmission filter. Thetransmission filter includes a plurality of serial arm resonatorselectrically connected in series to a serial arm electrically connectingthe shared terminal and the transmission terminal, a plurality ofparallel arm resonators each electrically connected in series to each ofa plurality of parallel arms electrically connecting the serial arm anda ground, a first inductor electrically connected between the ground anda connection end electrically connecting at least the two parallel armresonators of the plurality of parallel arm resonators, and a secondinductor electrically connected between the ground and one parallel armresonator different from the at least two parallel arm resonators of theplurality of parallel arm resonators. The second inductor is coupled, byelectromagnetic field coupling, to at least one element selected from agroup including the antenna side matching element, the transmission sidematching element, and a portion of the serial arm in the transmissionfilter, and the first inductor and the second inductor obstructelectromagnetic field coupling between the first and second inductors.

With the high frequency module of the preferred embodiment of thepresent invention described above, both isolation characteristics andharmonic attenuation characteristics of the transmission filter are ableto be significantly improved at the same time.

To be specific, the first inductor adjusts the harmonic attenuationcharacteristics of the transmission filter. For example, adjustinginductance of the first inductor causes an attenuation pole of theharmonic to change in the attenuation characteristics of thetransmission filter. The inductance of the first inductor is adjustedand the attenuation pole is set at the desired frequency.

In the high frequency module of the preferred embodiment of the presentinvention described above, the second inductor is coupled, byelectromagnetic field coupling, to at least one element selected fromthe group including the antenna side matching element, the transmissionside matching element, and a portion of the serial arm in thetransmission filter.

This electromagnetic field coupling defines an adjustment path separatefrom a main path from the transmission terminal to the shared terminal.By adjusting the mode and strength of the electromagnetic fieldcoupling, a transmission signal flowing to the shared terminal throughthe transmission filter is canceled out by a transmission signal flowingto the shared terminal through the adjustment path. Specifically, thecoupling mode and strength of the electromagnetic field coupling areadjusted and the amplitude of the transmission signal flowing to theshared terminal through the transmission filter and the amplitude of thetransmission signal flowing to the shared terminal through theadjustment path become the same or substantially the same, and thephases of the respective transmission signals differ from each other by180 degrees. The high frequency module is able to provide significantlyimproved isolation characteristics because the transmission signal thatcomes around and flowing to the reception terminal is attenuated.

In the high frequency module of the preferred embodiment of the presentinvention described above, the first inductor and the second inductorobstruct electromagnetic field coupling between the first and secondinductors.

Because of this, electromagnetic field coupling between the firstinductor and the second inductor is not generated. However, in thepreferred embodiment of the present invention described above, theexpression “electromagnetic field coupling is not generated” indicatesthat the design is carried out with the intention of significantlyreducing or preventing the generation of electromagnetic field coupling.Accordingly, the expression “electromagnetic field coupling is notgenerated” does not actually indicate that the electromagnetic fieldcoupling is not generated at all.

In the high frequency module of the preferred embodiment of the presentinvention described above, because the electromagnetic field couplingbetween the first inductor and the second inductor is obstructed, thefirst inductor and the second inductor are able to be separatelyadjusted without considering influence of the respective inductors. Inother words, for example, even if the inductance of the first inductoris adjusted in order to significantly improve the harmonic attenuationcharacteristics of the transmission filter, the isolationcharacteristics significantly improved by the electromagnetic fieldcoupling of the second inductor are maintained.

Because the high frequency module includes the first inductor and thesecond inductor that are not affected each other, both the significantimprovement in the isolation characteristics by the second inductor andthe significant improvement in the harmonic attenuation characteristicsof the transmission filter by the first inductor is able to be providedat the same time.

Note that, in the above description, the second inductor provides theadjustment path to significantly improve the isolation characteristics,while the first inductor is included to adjust the harmonic attenuationcharacteristics of the transmission filter. However, in the preferredembodiment of the present invention described above, the first inductorin place of the second inductor may be selected to define the adjustmentpath to significantly improve the isolation characteristics. In otherwords, the high frequency module of the preferred embodiment of thepresent invention described above may significantly improve theisolation characteristics by the electromagnetic field coupling of thefirst inductor and significantly improve the harmonic attenuationcharacteristics of the transmission filter by the second inductor.

The high frequency module of the preferred embodiment of the presentinvention described above may include the first inductor coupled, byelectromagnetic field coupling, to one element selected from the groupincluding the antenna side matching element, the transmission sidematching element, and a portion of the serial arm in the transmissionfilter.

In the above structure, a second adjustment path that adjusts theisolation characteristics is defined by the first inductor being coupledto another circuit element by electromagnetic field coupling.Accordingly, by adjusting the mode and strength of the electromagneticfield coupling defining the second adjustment path, the isolationcharacteristics of the high frequency module are further significantlyimproved.

The high frequency module of the preferred embodiment of the presentinvention described above may further include a reception side matchingelement electrically connected between the reception terminal and thereception filter, wherein the high frequency module may include thefirst inductor coupled, by electromagnetic field coupling, to at leastone element selected from a group including the antenna side matchingelement, the transmission side matching element, the reception sidematching element, a portion of the serial arm in the transmissionfilter, and a reception path from one end to the other end of thereception filter.

The above structure further significantly improves the isolationcharacteristics of the high frequency module.

A high frequency module according to a preferred embodiment of thepresent invention includes a shared terminal electrically connected toan antenna, a transmission terminal, a reception terminal, atransmission filter electrically connected between the shared terminaland the transmission terminal, a reception filter electrically connectedbetween the shared terminal and the reception terminal, and an antennaside matching element electrically connected between the shared terminaland a connection portion of the transmission filter and the receptionfilter, or a transmission side matching element electrically connectedbetween the transmission terminal and the transmission filter. Thetransmission filter includes a plurality of serial arm resonatorselectrically connected in series to a serial arm electrically connectingthe shared terminal and the transmission terminal, a plurality ofparallel arm resonators each electrically connected in series to each ofa plurality of parallel arms electrically connecting the serial arm anda ground, a first inductor electrically connected between the ground anda connection end electrically connecting at least the two parallel armresonators of the plurality of parallel arm resonators, and a secondinductor electrically connected between the ground and one parallel armresonator different from the at least two parallel arm resonators of theplurality of parallel arm resonators. The first inductor is coupled, byelectromagnetic field coupling, to at least one element selected from agroup including the antenna side matching element, the transmission sidematching element, and a portion of the serial arm in the transmissionfilter, and the first inductor and the second inductor obstructelectromagnetic field coupling between the first and second inductors.

With the high frequency module of the preferred embodiment of thepresent invention described above, both isolation characteristics andharmonic attenuation characteristics of the transmission filter are ableto be significantly improved at the same time.

The high frequency module of the preferred embodiment of the presentinvention described above may include the second inductor coupled, byelectromagnetic field coupling, to one element selected from the groupincluding the antenna side matching element, the transmission sidematching element, and a portion of the serial arm in the transmissionfilter.

In the above structure, a second adjustment path that adjusts theisolation characteristics is defined by the second inductor beingcoupled to another circuit element by electromagnetic field coupling.Accordingly, by adjusting the mode and strength of the electromagneticfield coupling defining the second adjustment path, the isolationcharacteristics of the high frequency module are further significantlyimproved.

The high frequency module of the preferred embodiment of the presentinvention described above may further include a reception side matchingelement electrically connected between the reception terminal and thereception filter, wherein the high frequency module may include thesecond inductor coupled, by electromagnetic field coupling, to at leastone element selected from a group including the antenna side matchingelement, the transmission side matching element, the reception sidematching element, a portion of the serial arm in the transmissionfilter, and a reception path from one end to the other end of thereception filter.

The above structure further significantly improves the isolationcharacteristics of the high frequency module.

The high frequency module may include circuitry and structure asdescribed below to significantly reduce or prevent the generation ofelectromagnetic field coupling between the first inductor and the secondinductor.

A high frequency module according to a preferred embodiment of thepresent invention may include a substrate, wherein the transmissionfilter may be mounted in or on the substrate, and the first inductor andthe second inductor may be located at different positions in a plan viewof the substrate.

The above structure further significantly improves the isolationcharacteristics and the harmonic attenuation characteristics of thetransmission filter.

In the high frequency module of the preferred embodiment of the presentinvention described above, one of the first inductor and the secondinductor may be provided, as a chip inductor, on a principal surface ofthe substrate, and the other one of the first inductor and the secondinductor may be provided inside the substrate. Also in this case, thefirst inductor and the second inductor may not overlap with each otherin a plan view of the substrate.

The above structure further significantly improves the isolationcharacteristics and the harmonic attenuation characteristics of thetransmission filter.

In the high frequency module of the preferred embodiment of the presentinvention described above, the first inductor and the second inductormay be arranged with a ground inside the substrate interposedtherebetween.

The above structure further significantly improves the isolationcharacteristics and the harmonic attenuation characteristics of thetransmission filter.

According to the preferred embodiments of the present invention, highfrequency modules that are excellent in isolation characteristics andalso excellent in harmonic attenuation characteristics of a transmissionfilter are provided.

The above and other elements, features, steps, characteristics, andadvantages of the present invention will become more apparent from thefollowing detailed description of preferred embodiments of the presentinvention with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit block diagram showing a first circuit example of ahigh frequency module according to a preferred embodiment of the presentinvention.

FIG. 2 is a circuit block diagram showing a second circuit example of ahigh frequency module according to a preferred embodiment of the presentinvention.

FIG. 3 is a circuit block diagram showing a third circuit example of ahigh frequency module according to a preferred embodiment of the presentinvention.

FIG. 4 is a circuit block diagram showing a fourth circuit example of ahigh frequency module according to a preferred embodiment of the presentinvention.

FIG. 5 is a circuit block diagram showing a fifth circuit example of ahigh frequency module according to a preferred embodiment of the presentinvention.

FIG. 6 is a circuit block diagram showing a sixth circuit example of ahigh frequency module according to a preferred embodiment of the presentinvention.

FIG. 7 is a circuit block diagram showing a seventh circuit example of ahigh frequency module according to a preferred embodiment of the presentinvention.

FIG. 8 is a circuit block diagram showing an eighth circuit example of ahigh frequency module according to a preferred embodiment of the presentinvention.

FIGS. 9A to 9H are circuit diagrams showing specific examples ofmatching circuits of the high frequency modules shown in FIG. 1 to FIG.8, respectively.

FIG. 10 is a graph showing isolation characteristics between a firstexternal connection terminal and a second external connection terminalof a high frequency module according to a preferred embodiment of thepresent invention.

FIG. 11 is a graph showing harmonic attenuation characteristics of atransmission signal filter of a high frequency module according to apreferred embodiment of the present invention.

FIG. 12 is a side surface conceptual diagram showing the main structureof a first structure of a high frequency module.

FIG. 13 is a side surface conceptual diagram showing the main structureof a second structure of a high frequency module.

FIG. 14 is a top surface conceptual diagram showing the main structureof a third structure of a high frequency module.

FIG. 15 is a side surface conceptual diagram showing the main structureof a fourth structure of a high frequency module.

FIG. 16 is a side surface conceptual diagram showing the main structureof a fifth structure of a high frequency module.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described withreference to FIGS. 1 to 16. Note that the following description is inall aspects illustrative and not restrictive and should not be construedto restrict the applications or implementations of the preferredembodiments of the present invention in any manner. High frequencymodules according to preferred embodiments of the present invention willbe described with reference to the drawings. In the following, thedescription is provided with respect to a duplexer as an example of ahigh frequency module. In the specification, “electromagnetic fieldcoupling” refers to electric field coupling, magnetic field coupling, orboth of them. In the drawings, “NO” indicates that electromagnetic fieldcoupling is not generated between circuits.

FIG. 1 is a circuit block diagram of a duplexer 101 of a first circuitexample. FIG. 2 is a circuit block diagram of a duplexer 101A of asecond circuit example. FIG. 3 is a circuit block diagram of a duplexer101B of a third circuit example. FIG. 4 is a circuit block diagram of aduplexer 101C of a fourth circuit example. FIG. 5 is a circuit blockdiagram of a duplexer 101D of a fifth circuit example. FIG. 6 is acircuit block diagram of a duplexer 101E of a sixth circuit example.Note that in FIGS. 1 to 6, in order to significantly improve thevisibility of the drawings, representative examples of inductivecoupling or capacitive coupling are shown.

First, a circuit common to the duplexers 101, 101A, 101B, 101C, 101D,and 101E respectively shown in FIGS. 1 to 6 will be described. In thefollowing, the duplexers 101, 101A, 101B, 101C, 101D, and 101E arecollectively referred to as duplexers 101-101E.

The duplexers 101-101E each include a first external connection terminalP1, a second external connection terminal P2, a third externalconnection terminal P3, a transmission signal filter 20, a receptionsignal filter 30, an inductor 41L, an inductor 42L, an inductor 50, andan inductor 60.

The transmission signal filter 20 is electrically connected between thefirst external connection terminal P1 and the third external connectionterminal P3. The reception signal filter 30 is electrically connectedbetween the second external connection terminal P2 and the thirdexternal connection terminal P3. The inductor 41L is a matching element,and is shunt-electrically connected to a path 401 between the firstexternal connection terminal P1 and the transmission signal filter 20.The inductor 42L is a matching element, and is shunt-electricallyconnected to a path 402 between the third external connection terminalP3 and the transmission signal filter 20.

The transmission signal filter 20 includes a series connection terminalP21, a series connection terminal P22, a shunt connection terminal P23,and a shunt connection terminal P24. The series connection terminal P21is electrically connected to the first external connection terminal Pb.The series connection terminal P22 is electrically connected to thethird external connection terminal P3.

The shunt connection terminal P23 is electrically connected to theground with the inductor 60 interposed therebetween. The shuntconnection terminal P24 is electrically connected to the ground with theinductor 50 interposed therebetween. The inductor 60 corresponds to asecond inductor, and the inductor 50 corresponds to a first inductor.

In the present application, the shunt connection refers to a connectionbetween a path and the ground. Further, the series connection refers toa connection in series between circuits.

The transmission signal filter 20 includes a plurality of SAW resonators201, 202, 203, 204, 205, and 206 (hereinafter, referred to as SAWresonators 201-206 when these SAW resonators are collectivelyexplained). The transmission signal filter 20 further includes aplurality of SAW resonators 211, 212, and 213. The SAW resonators201-206 correspond to serial arm resonators, and the SAW resonators 211,212, and 213 respectively correspond to parallel arm resonators.

The SAW resonators 201-206 are electrically connected in series betweenthe series connection terminal P21 and the series connection terminalP22. In other words, the SAW resonators 201-206 are electricallyconnected in series to a serial arm electrically connecting the firstexternal connection terminal P1 and the third external connectionterminal P3. To be specific, one end of the SAW resonator 201 iselectrically connected to the series connection terminal P21 with aconnection conductor 301 interposed therebetween while the other endthereof is electrically connected to one end of the SAW resonator 202.The other end of the SAW resonator 202 is electrically connected to oneend of the SAW resonator 203 with a connection conductor 302 interposedtherebetween. The other end of the SAW resonator 203 is electricallyconnected to one end of the SAW resonator 204. The other end of the SAWresonator 204 is electrically connected to one end of the SAW resonator205 with a connection conductor 303 interposed therebetween. The otherend of the SAW resonator 205 is electrically connected to one end of theSAW resonator 206. The other end of the SAW resonator 206 iselectrically connected to the series connection terminal P22 with aconnection conductor 304 interposed therebetween.

The SAW resonators 211, 212, and 213 are respectively electricallyconnected to a plurality of parallel arms electrically connecting theground and the serial arm between the first external connection terminalP1 and the third external connection terminal P3. To be specific, oneend of the SAW resonator 213 is electrically connected to the connectionconductor 301 while the other end thereof is electrically connected tothe shunt connection terminal P24. One end of the SAW resonator 212 iselectrically connected to the connection conductor 302 while the otherend thereof is electrically connected to the shunt connection terminalP24. In other words, the shunt connection terminal P24 is a terminalcommon to the SAW resonators 212 and 213, and collects and electricallyconnects the other ends of the SAW resonators 212 and 213 to the ground.One end of the SAW resonator 211 is electrically connected to theconnection conductor 303 while the other end thereof is electricallyconnected to the shunt connection terminal P23.

The SAW resonators 201-206, 211, 212, and 213 respectively provideresonant frequencies. With the above-discussed circuitry and structure,the transmission signal filter 20 defines a ladder connection filter andprovides the desired bandpass characteristics and attenuationcharacteristics as the transmission signal filter 20 by combining theSAW resonators 201-206, 211, 212, and 213. In the transmission signalfilter 20, the number of SAW resonators, the arrangement thereof, or thelike may be appropriately changed to provide the frequency band of asignal to be passed and the desired attenuation characteristics.

The reception signal filter 30 includes a series connection terminalP33, a SAW resonator 31, a longitudinally coupled SAW resonator 32, alongitudinally coupled SAW resonator 33, a matching circuit 34, andbalanced connection terminals P2A and P2B.

The series connection terminal P33 is electrically connected to thethird external connection terminal P3 with a connection conductor 403interposed therebetween. One end of the SAW resonator 31 is electricallyconnected to the series connection terminal P33 while the other endthereof is electrically connected to one end of the SAW resonator 32with a connection conductor 312 interposed therebetween. Thelongitudinally coupled SAW resonator 32 provides a balanced-unbalancedtransforming feature. The other end of the SAW resonator 32 iselectrically connected to one end of the SAW resonator 33 in a balancedarrangement. The other end of the SAW resonator 33 is electricallyconnected to one end of the matching circuit 34. The matching circuit 34includes an inductor and a capacitor. The other end of the matchingcircuit 34 is electrically connected to the balanced connectionterminals P2A and P2B. The balanced connection terminals P2A and P2B areelectrically connected to the second external connection terminal P2 asa balanced terminal. Note that, however, it is not necessary for thecircuitry and structure of the reception signal filter 30 to provide thebalanced-unbalanced transforming feature in the present preferredembodiment. Accordingly, the second external connection terminal P2 andthe balanced connection terminals P2A, P2B of the reception signalfilter 30 may respectively be unbalanced terminals.

As described below, in the duplexers 101-101E according to the presentpreferred embodiment, the inductor 50 and the inductor 60 obstructelectromagnetic field coupling between the inductors 50 and 60. Becauseof this, electromagnetic field coupling between the inductor 50 and theinductor 60 is not generated. However, in the present preferredembodiment, the expression “electromagnetic field coupling is notgenerated” or “electromagnetic field coupling is obstructed” indicatesthat the design is carried out with the intention of significantlyreducing or preventing the generation of electromagnetic field coupling.Accordingly, the expression “electromagnetic field coupling is notgenerated” or “electromagnetic field coupling is obstructed” does notactually indicate that the electromagnetic field coupling is notgenerated at all.

By significantly reducing or preventing the generation ofelectromagnetic field coupling between the inductor 50 and the inductor60, the inductance of the inductors 50 and 60 is able to be adjustedseparately without the inductors 50 and 60 being affected each other. Asa result, isolation characteristics of the duplexers 101-101E andharmonic attenuation characteristics of the transmission signal filter20 are able to be both significantly improved. Accordingly, with theinductor 50 (first inductor) and the inductor 60 (second inductor) thatare not affected each other, both the significant improvement in theisolation characteristics of the duplexers 101-101E and the significantimprovement in the harmonic attenuation characteristics of thetransmission signal filter 20 are able to be provided at the same time.

First Circuit Example

In the duplexer 101 as shown in FIG. 1, the inductor 50 and the inductor60 obstruct electromagnetic field coupling between the inductors 50 and60. For example, a ground is located between the inductor 60 and theinductor 50, or the inductor 60 and the inductor 50 are spaced with adistance therebetween longer than a distance between the inductor 60 andthe inductor 42L. This significantly reduces or prevents the generationof electromagnetic field coupling between the inductor 50 and theinductor 60, and thus the inductor 60 and the inductor 50 are able to beseparately adjusted.

The inductor 60, which is not coupled to the inductor 50 byelectromagnetic field coupling, and the inductor 42L includeelectromagnetic field coupling (capacitive coupling or inductivecoupling) generated therebetween. With this electromagnetic fieldcoupling, an adjustment path that adjusts the isolation characteristicsis defined. The adjustment path includes the connection conductor 303,the SAW resonator 211, the shunt connection terminal P23, the inductor60, and the inductor 42L.

The coupling mode and strength of the electromagnetic field couplingthat defines the adjustment path are adjusted, and a transmission signalthat passes through the transmission signal filter 20 and the path 402from the first external connection terminal P1 and a transmission signalthat passes through the adjustment path are canceled out at the thirdexternal connection terminal P3. Specifically, the mode and strength ofthe electromagnetic field coupling between the inductor 60 and theinductor 42L are adjusted, and at the third external connection terminalP3, the amplitudes of the transmission signal passing through thetransmission signal filter 20 and the path 402 from the first externalconnection terminal P1 and the transmission signal passing through theadjustment path are the same or substantially the same, and the phasesof the respective transmission signals are different from each other by180 degrees. The mode of electromagnetic field coupling includes theinductive coupling between the inductor 60 and the inductor 42L and thecapacitive coupling between the conductors defining the inductor 60 andthe inductor 42L. The strength of the electromagnetic field coupling isdetermined in accordance with the distance between the inductor 60 andthe inductor 42L, for example. By adjusting the mode and strength of theelectromagnetic field coupling, the transmission signal passing throughthe transmission signal filter 20 and the path 402 from the firstexternal connection terminal P1 is canceled out by the transmissionsignal flowing through the adjustment path, thus increasing attenuationof the transmission signal in the transmission path. As a result, sincethe transmission signal is also attenuated at the second externalconnection terminal P2, isolation characteristics between transmissionand reception of the duplexer 101 are significantly improved.

The inductance of the inductor 50, which is not coupled to the inductor60 by electromagnetic coupling, is adjusted and the harmonic attenuationcharacteristics of the transmission signal filter 20 provide the desiredcharacteristics at the third external connection terminal P3. The changein the inductance of the inductor 50 causes the attenuation pole of aharmonic region in the attenuation characteristics of the transmissionsignal filter 20 to change. The inductance of the inductor 50 is set toprovide the attenuation pole at the desired frequency in the attenuationcharacteristics of the transmission signal filter 20.

A harmonic frequency of the transmission signal or the like is able tobe provided, for example, as the desired frequency attenuated by theattenuation pole set by the change of the inductance of the inductor 50,which is not coupled to the inductor 60 by electromagnetic fieldcoupling. As the harmonic of the transmission signal, a second-orderharmonic, a third-order harmonic, or the like of the transmission signalis able to be provided.

In the duplexer 101 as shown in FIG. 1, the inductor 50 and the inductor60 is able to be separately adjusted because electromagnetic fieldcoupling between the inductor 50 and the inductor 60 is significantlyreduced or prevented from being generated. As such, even if theinductance of the inductor 50 is adjusted, the isolation characteristicsof the duplexer 101 are not affected by the adjustment. Likewise, evenif the mode and strength of the electromagnetic field coupling betweenthe inductor 60 and the inductor 42L are adjusted, the harmonicattenuation characteristics of the transmission signal filter 20 are notaffected. As a result, the duplexer 101 is able to significantly improvethe isolation characteristics between the transmission and reception andsignificantly improve the harmonic attenuation characteristics of thetransmission signal filter 20 at the same time.

Second Circuit Example

The duplexer 101A shown in FIG. 2 differs from the duplexer 101 shown inFIG. 1 in the following point. In the duplexer 101A, by the generationof electromagnetic field coupling between an inductor 60A and theinductor 41L, an adjustment path is provided, thus significantlyimproving isolation characteristics between the transmission andreception. That is, in the present example, the adjustment path thatsignificantly improves the isolation characteristics includes theinductor 41L, the inductor 60A, the shunt connection terminal P23, theSAW resonator 211, and the connection conductor 303.

As shown in FIG. 2, the inductor 60A and the inductor 50 obstructelectromagnetic field coupling between the inductors 60A and 50, also inthe duplexer 101A. For example, a ground is located between the inductor60A and the inductor 50, or the inductor 60A and the inductor 50 arespaced by a distance therebetween longer than a distance between theinductor 60A and the inductor 41L. Accordingly, the inductor 60A and theinductor 50 are able to be adjusted separately.

As such, even if the inductance of the inductor 50 is adjusted, theisolation characteristics of the duplexer 101A are not affected by theadjustment. Likewise, even if the mode and strength of theelectromagnetic field coupling between the inductor 60A and the inductor41L are adjusted, the harmonic attenuation characteristics of thetransmission signal filter 20 are not affected. As a result, theduplexer 101A is able to significantly improve the isolationcharacteristics between the transmission and reception and significantlyimprove the harmonic attenuation characteristics of the transmissionsignal filter 20 at the same time.

Third Circuit Example

The duplexer 101B shown in FIG. 3 differs from the duplexer 101 shown inFIG. 1 in the following point. In the duplexer 101B, by the generationof electromagnetic field coupling between an inductor 60B and theconnection conductor 302, an adjustment path is provided, thussignificantly improving isolation characteristics between thetransmission and reception. That is, in the present example, theadjustment path that significantly improves the isolationcharacteristics includes the connection conductor 302, the inductor 60B,the shunt connection terminal P23, the SAW resonator 211, and theconnection conductor 303.

As shown in FIG. 3, the inductor 60B and the inductor 50 obstructelectromagnetic field coupling between the inductors 60B and 50, also inthe duplexer 101B. For example, a ground is located between the inductor60B and the inductor 50, or the inductor 60B and the inductor 50 arespaced by a distance therebetween longer than a distance between theinductor 60B and the connection conductor 302. Accordingly, the inductor60B and the inductor 50 are able to be adjusted separately.

As such, even if the inductance of the inductor 50 is adjusted, theisolation characteristics of the duplexer 101B are not affected by theadjustment. Likewise, even if the mode and strength of theelectromagnetic field coupling between the inductor 60B and theconnection conductor 302 are adjusted, the harmonic attenuationcharacteristics of the transmission signal filter 20 are not affected.As a result, the duplexer 101B is able to significantly improve theisolation characteristics between the transmission and reception andsignificantly improve the harmonic attenuation characteristics of thetransmission signal filter 20 at the same time.

The third circuit example may be in a mode in which an adjustment pathis provided by the generation of electromagnetic field coupling betweenthe inductor 60B and the connection conductor 301, between the inductor60B and the connection conductor 303, or between the inductor 60B andthe connection conductor 304.

Fourth Circuit Example

The duplexer 101C shown in FIG. 4 differs from the duplexer 101 shown inFIG. 1 in the following point. In the duplexer 101C, by the generationof electromagnetic field coupling between an inductor 60C and theconnection conductor 403, an adjustment path is provided, thussignificantly improving isolation characteristics between thetransmission and reception. That is, in the present example, theadjustment path that significantly improves the isolationcharacteristics includes the connection conductor 403, the inductor 60C,the shunt connection terminal P23, the SAW resonator 211, and theconnection conductor 303.

As shown in FIG. 4, the inductor 60C and the inductor 50 obstructelectromagnetic field coupling therebetween also in the duplexer 101C.For example, a ground is located between the inductor 60C and theinductor 50, or the inductor 60C and the inductor 50 are spaced by adistance therebetween longer than a distance between the inductor 60Cand the connection conductor 403. Accordingly, the inductor 60C and theinductor 50 are able to be adjusted separately.

As such, even if the inductance of the inductor 50 is adjusted, theisolation characteristics of the duplexer 101C are not affected by theadjustment. Likewise, even if the mode and strength of theelectromagnetic field coupling between the inductor 60C and theconnection conductor 403 are adjusted, the harmonic attenuationcharacteristics of the transmission signal filter 20 are not affected.As a result, the duplexer 101C is able to significantly improve theisolation characteristics between the transmission and reception andsignificantly improve the harmonic attenuation characteristics of thetransmission signal filter 20 at the same time.

Fifth Circuit Example

The duplexer 101D shown in FIG. 5 differs from the duplexer 101 shown inFIG. 1 in the following point. In the duplexer 101D, by the generationof electromagnetic field coupling between an inductor 60D and theconnection conductor 312 in the reception signal filter 30, anadjustment path is provided, thus significantly improving isolationcharacteristics between the transmission and reception. That is, in thepresent example, the adjustment path that significantly improves theisolation characteristics includes the connection conductor 312, theinductor 60D, the shunt connection terminal P23, the SAW resonator 211,and the connection conductor 303.

As shown in FIG. 5, the inductor 60D and the inductor 50 obstructelectromagnetic field coupling between the inductors 60D and 50, also inthe duplexer 101D. For example, a ground is located between the inductor60D and the inductor 50. Alternatively, the inductor 60D and theinductor 50 are spaced by a distance therebetween longer than a distancebetween the inductor 60D and the connection conductor 312. Accordingly,the inductor 60D and the inductor 50 are able to be adjusted separately.

As such, even if the inductance of the inductor 50 is adjusted, theisolation characteristics of the duplexer 101D are not affected by theadjustment. Likewise, even if the mode and strength of theelectromagnetic field coupling between the inductor 60D and theconnection conductor 312 are adjusted, the harmonic attenuationcharacteristics of the transmission signal filter 20 are not affected.As a result, the duplexer 101D is able to significantly improve theisolation characteristics between the transmission and reception andsignificantly improve the harmonic attenuation characteristics of thetransmission signal filter 20 at the same time.

Sixth Circuit Example

The duplexer 101E shown in FIG. 6 differs from the duplexer 101 shown inFIG. 1 in the following point. In the duplexer 101E, by the generationof electromagnetic field coupling between an inductor 60E and thematching circuit 34 in the reception signal filter 30, an adjustmentpath is provided, thus significantly improving isolation characteristicsbetween the transmission and reception. That is, in the present example,the adjustment path that adjusts the attenuation of a transmissionsignal to significantly improve the isolation characteristics includesthe matching circuit 34, the inductor 60E, the shunt connection terminalP23, the SAW resonator 211, and the connection conductor 303.

As shown in FIG. 6, also in the duplexer 101E, to obstructelectromagnetic field coupling between the inductors 60E and 50, aground is located between the inductor 60E and the inductor 50, or theinductor 60E and the inductor 50 are spaced by a distance therebetweenlonger than a distance between the inductor 60E and the matching circuit34 in the filter 30. Accordingly, the inductor 60E and the inductor 50are able to be adjusted separately.

As such, even if the inductance of the inductor 50 is adjusted, theisolation characteristics of the duplexer 101E are not affected by theadjustment. Likewise, even if the mode and strength of theelectromagnetic field coupling between the inductor 60E and the matchingcircuit 34 are adjusted, the harmonic attenuation characteristics of thetransmission signal filter 20 are not affected. As a result, theduplexer 101E is able to significantly improve the isolationcharacteristics between the transmission and reception and significantlyimprove the harmonic attenuation characteristics of the transmissionsignal filter 20 at the same time.

Although, in the above-discussed examples, electromagnetic fieldcoupling is generated between each of the inductors 60 to 60E and onecircuit element, electromagnetic field coupling may be generated betweeneach of the inductors 60 to 60E and two or more circuit elements. Inother words, the duplexers 101-101E may include a plurality ofadjustment paths through the inductors 60 to 60E.

Further, in the above examples, at least one circuit element and one ofthe inductors 60 to 60E are coupled by electromagnetic field coupling,and thus the above one of the inductors 60 to 60E defines an adjustmentpath and consequently the isolation characteristics between thetransmission and reception are significantly improved. The harmonicattenuation characteristics of the transmission signal filter 20 aresignificantly improved by the inductor 50, which is not coupled byelectromagnetic field coupling to any of the inductors 60 to 60E. Asdiscussed below, as an inductor that is coupled, by electromagneticfield coupling, to at least one circuit element to define an adjustmentpath that significantly improves the isolation characteristics, theinductor 50 may be selected in place of the inductors 60 to 60E.

Seventh Circuit Example

FIG. 7 is a circuit block diagram of a duplexer 101F of a seventhcircuit example. As shown in FIG. 7, in the duplexer 101F, by thegeneration of electromagnetic field coupling between an inductor 50F andthe inductor 42L, an adjustment path is provided. Electromagnetic fieldcoupling between an inductor 60F and the inductor 50F is obstructed.

In other words, by the generation of the electromagnetic field couplingbetween the inductor 50F and the inductor 42L, the above-mentionedadjustment path is provided, thus significantly improving the isolationcharacteristics between the transmission and reception of the duplexer101F. In the duplexer 101F, the inductor 60F is included to adjust theharmonic attenuation characteristics of the transmission signal filter20.

The inductor 60F and the inductor 50F obstruct electromagnetic fieldcoupling between the inductors 60F and 50F also in the duplexer 101F ofthe seventh circuit example. For example, a ground is located betweenthe inductor 60F and the inductor 50F. Alternatively, the inductor 60Fand the inductor 50F are spaced by a distance therebetween longer than adistance between the inductor 50F and the inductor 42L. Accordingly, theinductor 60F and the inductor 50F are able to be adjusted separately.

As such, even if the inductance of the inductor 60F is adjusted, theisolation characteristics of the duplexer 101F are not affected by theadjustment. Likewise, even if the mode and strength of theelectromagnetic field coupling between the inductor 50F and the inductor42L are adjusted, the harmonic attenuation characteristics of thetransmission signal filter 20 are not affected. As a result, theduplexer 101F is able to significantly improve the isolationcharacteristics between the transmission and reception and significantlyimprove the harmonic attenuation characteristics of the transmissionsignal filter 20 at the same time.

Although not shown, an adjustment path that significantly improves theisolation characteristics is not limited to the example in which theadjustment path is provided by the electromagnetic field couplinggenerated between the inductor 50F and the inductor 42L. The adjustmentpath may be defined by the generation of electromagnetic field couplingbetween the inductor 50F and at least one element selected from a groupincluding the inductors 41L and 42L, the connection conductors 301 to304, the connection conductor 403, the connection conductor 312, and thematching circuit 34.

Eighth Circuit Example

FIG. 8 is a circuit block diagram of a duplexer 101G of an eighthcircuit example. In the duplexer 101G, electromagnetic field coupling isalso generated between an inductor 50G and the inductor 41L. That is, inthe eighth circuit example, the electromagnetic field coupling isgenerated between the inductor 50G and the inductor 41L, which is notcoupled to the inductor 60 by electromagnetic field coupling.

The inductor 60 and the inductor 50G obstruct electromagnetic fieldcoupling between the inductors 60 and 50G also in the duplexer 101G. Forexample, a ground is located between the inductor 60 and the inductor50G. Alternatively, the inductor 60 and the inductor 50G are spaced by adistance therebetween longer than a distance between the inductor 60 andthe inductor 42L and/or a distance between the inductor 50G and theinductor 41L. Accordingly, the inductor 60 and the inductor 50G are ableto be adjusted separately.

In the present example, an adjustment path is further provided by theelectromagnetic field coupling generated between the inductor 50G andthe inductor 41L. The isolation characteristic are significantlyimproved by adjusting the mode and strength of the electromagnetic fieldcoupling generated between the inductor 50G and the inductor 41L. Inother words, in the eighth circuit example, the isolationcharacteristics are further significantly improved due to the adjustmentpath of the inductors 50G and 41L, and an adjustment path byelectromagnetic field coupling generated between the inductor 60 and theinductor 42L.

Note that in the above examples, as a matching element on the firstexternal connection terminal P1 side, the inductor 41L as a shuntconnection matching element is indicated; as a matching element on thethird external connection terminal P3 side, the shunt connectioninductor 42L is indicated. However, the following components may beincluded as the matching elements on the first external connectionterminal P1 side and the third external connection terminal P3 side.

To be specific, the matching element on the first external connectionterminal P1 side is not limited to the inductor 41L shown in FIG. 9A,and may be a shunt connection capacitor 41C shown in FIG. 9B, a seriesconnection inductor 43L shown in FIG. 9C, or a series connectioncapacitor 43C shown in FIG. 9D.

The matching element on the third external connection terminal P3 sideis not limited to the inductor 42L shown in FIG. 9E, and may be a shuntconnection capacitor 42C shown in FIG. 9F, a series connection inductor44L shown in FIG. 9G, or a series connection capacitor 44C shown in FIG.9H.

In the case where an inductor is included as a matching element coupledto the inductor 50 or the inductor 60 by electromagnetic field coupling,strength of inductive coupling is increased. In the case where acapacitor is included as the matching element coupled to the inductor 50or the inductor 60 by electromagnetic field coupling, strength ofcapacitive coupling is increased.

However, it may be sufficient for the duplexer according to a preferredembodiment of the present invention to include one of the matchingelement on the first external connection terminal P1 side and thematching element on the third external connection terminal P3 side.Further, a matching circuit in which the elements shown in FIGS. 9A to9H are combined may be arranged on the first external connectionterminal P1 side (third external connection terminal P3 side).

Next, FIG. 10 is a graph showing isolation characteristics of theduplexer 101 shown in FIG. 1. The horizontal axis of FIG. 10 representsa frequency, and the longitudinal axis thereof represents an isolationamount. Note that the isolation amount shown in FIG. 10 indicates theamount of isolation between the first external connection terminal P1and the second external connection terminal P2.

In FIG. 10, a thick solid line indicates isolation characteristics ofthe duplexer 101 according to a working example of the presentapplication. To be specific, the duplexer 101 according to the workingexample obstructs electromagnetic field coupling between the inductor 50and the inductor 60, and an adjustment path is provided byelectromagnetic field coupling between the inductor 60 and the inductor42L. In FIG. 10, a thin solid line indicates isolation characteristicsof a duplexer according to a first comparative example. To be specific,in the duplexer according to the first comparative example, anadjustment path that significantly improves isolation is not defined. InFIG. 10, a dotted line indicates isolation characteristics of a duplexeraccording to a second comparative example. To be specific, the duplexeraccording to the second comparative example includes the same orsubstantially the same circuitry as the duplexer 101 according to theworking example except that electromagnetic field coupling is generatedbetween the inductor 50 and the inductor 60.

As shown in FIG. 10, the isolation characteristics of the duplexer 101according to the working example are significantly improved in a rangefrom about 885 MHz to about 897.5 MHz, for example, in comparison withthe isolation characteristics of the duplexer according to the firstcomparative example. Due to the adjustment path defined by theelectromagnetic field coupling between the inductor 60 and the inductor42L, a transmission signal that flows to the third external connectionterminal P3 through the transmission signal filter 20 of the duplexer101 according to the working example is canceled out by a transmissionsignal that flows to the third external connection terminal P3 throughthe adjustment path, and thus a transmission signal that comes aroundand flowing to the second external connection terminal P2 is attenuated.As a result, the isolation characteristics between the transmission andreception are significantly improved. The duplexer according to thesecond comparative example in which the adjustment path is provided bythe inductor 50 and the inductor 60 and the duplexer 101 according tothe working example of the present application provide the same orsubstantially the same level of isolation amount.

Next, FIG. 11 is a graph showing harmonic attenuation characteristics ofthe transmission signal filter 20 of the duplexer 101 shown in FIG. 1.The horizontal axis of FIG. 11 represents a frequency; the longitudinalaxis thereof represents attenuation of a transmission signal propagatingfrom the first external connection terminal P1 to the third externalconnection terminal P3. A solid line in FIG. 11 indicates harmonicattenuation characteristics of the filter 20 of the duplexer 101according to the working example. A dotted line in FIG. 11 indicatesharmonic attenuation characteristics of the transmission filter of theduplexer according to the second comparative example.

Note that the transmission filters (transmission signal filter 20) ofthe duplexers according to the second comparative example and theworking example are respectively set to have an about 800 MHz band asthe pass band. The duplexer 101 according to the working exampleobstructs electromagnetic field coupling between the inductor 50 and theinductor 60, and an adjustment path is provided, by the electromagneticfield coupling, between the inductor 60 and the inductor 42L. Theduplexer according to the second comparative example includes the sameor substantially the same circuitry as the duplexer 101 according to theworking example except that the electromagnetic field coupling isgenerated between the inductor 50 and the inductor 60.

As shown in FIG. 11, in the duplexer according to the second comparativeexample, attenuation in the range from about 1.0 GHz to about 3.2 GHzwas from about 28 dB to about 40 dB. Meanwhile, in the duplexer 101according to the working example, attenuation in the range from about1.0 GHz to about 3.2 GHz was no less than about 40 dB. In other words,in the range from about 2.0 GHz to about 3.0 GHz, which is a harmonic ofthe transmission band of the transmission signal filter 20, theattenuation in the duplexer 101 according to the working example wasgreater than the attenuation in the duplexer according to thecomparative example by no less than about 10 dB. That is, in theduplexer 101 according to the working example, the harmonic attenuationcharacteristics of the transmission signal filter 20 were significantlyimproved in comparison with the duplexer according to the secondcomparative example.

The inductance of the inductor 50 was adjusted in order to adjust theharmonic attenuation characteristics of the filter 20. However, theisolation characteristics of the duplexer 101 shown in FIG. 10 werehardly affected. The mode and strength of the electromagnetic fieldcoupling between the inductor 60 and the inductor 42L were adjusted inorder to adjust the isolation characteristics. However, the harmonicattenuation characteristics of the filter 20 shown in FIG. 11 werehardly affected. In other words, in the duplexer 101 according to theworking example, the isolation characteristics and the harmonicattenuation characteristics of the transmission signal filter 20 wereable to be separately adjusted. As a result, the duplexer 101 accordingto the working example was able to significantly improve the isolationcharacteristics and able to significantly improve the harmonicattenuation characteristics of the transmission signal filter 20 at thesame time.

Structures of the duplexers according to preferred embodiments of thepresent invention are described below. Of the above-discussed duplexers101 to 101F, the duplexer 101 is taken as a representative and itsstructure is described below.

First Structure

FIG. 12 is a side surface conceptual diagram showing the main structureof a first structure of the duplexer 101. The duplexer 101 includes alamination substrate 100, a filter substrate 200, a cover layer 290, aside cover layer 291, and a mount circuit element 420. The side surfaceof the duplexer 101 is a surface orthogonal or substantially orthogonalto a top surface 100S of the lamination substrate 100 on which thefilter substrate 200 is mounted.

The lamination substrate 100 is provided by laminating a plurality ofdielectric layers. On the top surface (mounting surface) 100S of thelamination substrate 100 and in an inner layer thereof, electrodes withpredetermined patterns are formed, and wiring patterns, except for thetransmission signal filter 20 and reception signal filter 30 of theduplexer 101, are formed. For example, in the first structure, theinductor 50 and the inductor are provided in or on the inner layer ofthe lamination substrate 100.

The inductor 50 includes a linear electrode (linear conductor). One endof the linear electrode is electrically connected to a land electrode,with a via conductor 51V interposed therebetween, on which a mountingelectrode 294 defining and functioning as the shunt connection terminalP24 of the transmission signal filter 20 is mounted. The land electrodeis provided on the top surface 100S of the lamination substrate 100. Theother end of the linear electrode defining the inductor 50 iselectrically connected to an internal ground pattern provided inside thelamination substrate 100 with a via conductor 52V interposedtherebetween.

The inductor 60 includes a linear electrode (linear conductor). One endof the linear electrode is electrically connected to a land electrode,with a via conductor 61V interposed therebetween, on which the mountingelectrode 294 defining and functioning as the shunt connection terminalP23 of the transmission signal filter 20 is mounted. The land electrodeis provided on the top surface 100S of the lamination substrate 100. Theother end of the linear electrode defining the inductor 60 iselectrically connected to the internal ground pattern provided insidethe lamination substrate 100 with a via conductor 62V interposedtherebetween.

External connection electrodes are provided on a bottom surface 100R ofthe lamination substrate 100, and these external connection electrodesprovide the first external connection terminal P1, the second externalconnection terminal P2, and the third external connection terminal P3.The bottom surface 100R of the lamination substrate 100 is a surfaceopposing the top surface 100S of the lamination substrate 100 on whichthe filter substrate 200 is mounted.

The transmission signal filter 20 and the reception signal filter 30 areprovided by the filter substrate 200, the cover layer 290, the sidecover layer 291, a connection electrode 293, and the mounting electrode294.

The filter substrate 200 is a plate-shaped piezoelectric substrate. Afilter electrode and a wiring pattern are provided on a first principalsurface of the filter substrate 200. The filter electrode is, forexample, an interdigital transducer (IDT) electrode. With the abovestructure, by including the IDT electrodes on the principal surface ofthe piezoelectric substrate, the above-discussed SAW resonators are ableto be provided. The plate-shaped cover layer 290 is located on the firstprincipal surface side of the filter substrate 200. The cover layer 290includes a plate-shaped insulative material and includes the same orsubstantially the same shape as the filter substrate 200 in a plan view.Further, the cover layer 290 overlaps with the filter substrate 200 in aplan view, and is spaced from the first principal surface of the filtersubstrate 200 by a predetermined distance. Viewing the cover layer 290in a plan view indicates viewing the cover layer 290 along the normaldirection of the top surface 100S in a state in which the filtersubstrate 200 is mounted on the top surface 100S of the laminationsubstrate 100.

The side cover layer 291 is located between the first principal surfaceof the filter substrate 200 and the cover layer 290. The side coverlayer 291 also includes an insulative material, and extends across thewhole circumference of the filter substrate 200 and the cover layer 290only in a predetermined width range from the circumference edge towardthe inner side in a plan view. In other words, the side cover layer 291includes a frame-shaped structure at the center of which an opening isprovided.

By the cover layer 290 and the side cover layer 291 being structured asdescribed above, a region of the first principal surface of the filtersubstrate 200 where the filter electrode is provided is located in anenclosed space 292 by the filter substrate 200, the cover layer 290, andthe side cover layer 291. With this, resonance characteristics of theSAW resonators are able to be significantly improved and the desiredcharacteristics as the filter are able to be provided with precision.

The connection electrode 293 includes a shape in which one end thereofcontacts with the first principal surface of the filter substrate 200while the other end thereof is exposed to a surface of the cover layer290 on the opposite side to the filter substrate 200 side. In this case,the connection electrode 293 passes through the side cover layer 291 andthe cover layer 290. The one end of the connection electrode 293 iselectrically connected to the wiring pattern provided on the firstprincipal surface of the filter substrate 200.

The mounting electrode 294 electrically connects to the other end of theconnection electrode 293 and projects from the surface of the coverlayer 290 on the opposite side to the filter substrate 200 side. Byproviding a plurality of combinations of the connection electrode 293and the mounting electrode 294, the above-discussed series connectionterminal P21, series connection terminal P22, shunt connection terminalP23, shunt connection terminal P24, series connection terminal P33,balanced connection terminal P2A, and balanced connection terminal P2Bof the transmission signal filter 20 and the reception signal filter 30are able to be provided. A bump of solder, Au, or the like may be formedon the other end of the connection electrode 293, and the connectionelectrode 293 may be electrically connected to the mounting electrode294 with the bump interposed therebetween.

With the above circuitry and structure, the transmission signal filter20 and the reception signal filter 30 include a wafer level package(WLP) structure, and thus the transmission signal filter 20 and thereception signal filter 30 are able to be compact.

Then, the transmission signal filter 20 and reception signal filter 30of the WLP structure are mounted on the top surface 100S of thelamination substrate 100. With this, the transmission signal filter 20and the reception signal filter 30 are electrically connected to thefirst external connection terminal P1, the second external connectionterminal P2, and the third external connection terminal P3.

The inductor 42L is provided by the mount circuit element 420.Specifically, the mount circuit element 420 includes a rectangularparallelepiped or substantially rectangular parallelepiped housingincluding an insulative material, and a spiral electrode defining andfunctioning as the inductor 42L is provided inside the housing. Thespiral electrode extends along the circumference of the housing andincludes linear electrodes and interlayer connection electrodes. Thelinear electrodes in the respective layers are electrically connected bythe interlayer connection electrode to become a single linear electrode.Both ends of the spiral electrode are electrically connected to externalconnection electrodes on both end surfaces of the housing opposing eachother.

The mount circuit element 420 including the above-discussed circuitryand structure is mounted on the top surface 100S of the laminationsubstrate 100 with the center axis of the spiral electrode is orthogonalor substantially orthogonal to the top surface 100S. Note that, however,the mount circuit element 420 may be mounted with the center axis of thespiral electrode is parallel or substantially parallel to the topsurface 100S.

Although not shown, the inductor 41L is also provided by a mount circuitelement. However, the inductors 41L and 42L may be provided by thelinear electrodes located on the top surface 100S of the laminationsubstrate 100. Further, the inductors 41L and 42L may also be providedby the linear electrodes provided inside the lamination substrate 100.Then, as shown in FIG. 12, the mount circuit element 420 that providesthe inductor 42L and the linear electrode defining the inductor 60 areclose to each other. Thus, inductive coupling is able to be generatedbetween the inductor 42L including the spiral electrode in the mountcircuit element 420 and the inductor 60 including the linear electrodeinside the lamination substrate 100, as indicated by a thick broken linearrow mark in FIG. 12. Although not shown, in the case where a capacitoris included as the matching element on the third external connectionterminal P3 side, capacitive coupling is generated between the linearelectrode defining the inductor 60 and the capacitor.

In this case, by changing a distance between the linear electrodedefining the inductor 60 and the spiral electrode defining the inductor42L, strength of the electromagnetic field coupling between the inductor42L and the inductor 60 is able to be adjusted. Thus, the isolationcharacteristics of the duplexer 101 are able to be adjusted and thedesired isolation characteristics are able to be more preciselyprovided. Further, by adjusting the length of the linear electrodedefining the inductor 60, frequency characteristics of the transmissionsignal that flows in the adjustment path are able to be adjusted.Furthermore, by adjusting a path length of the adjustment path, thephase of the transmission signal, after passing through the adjustmentpath, is able to be adjusted at the second external connection terminalP2.

In the first structure of the duplexer 101, the linear electrodedefining the inductor 50 and the linear electrode defining the inductor60 are spaced from each other. In the structure shown in FIG. 12, thelinear electrodes are spaced from each other in a plane direction. Forexample, the inductor 60 and the inductor 50 are spaced by the distancetherebetween longer than the distance between the inductor 60 and theinductor 42L. As shown in the side surface conceptual diagram of FIG.12, the inductor 50 is located on one side surface side of thelamination substrate 100; the inductor 60 is located on the other sidesurface side of the lamination substrate 100 opposing the one sidesurface side, for example, in a region overlapping with the mountcircuit element 420 in a plan view of the duplexer 101. Because of this,inductive coupling between the inductor 50 and the inductor 60 is notgenerated. The linear electrodes may be spaced from each other in alamination direction in addition to the plane direction. Further, acircuit to obstruct inductive coupling between the inductor 50 and theinductor 60 may be provided between the inductors 50 and 60. Forexample, by providing a ground or the like between the inductor 50 andthe inductor 60, inductive coupling between the inductors 50 and 60 maybe obstructed.

Further, in order to obstruct inductive coupling between the inductor 50and the inductor 60, the linear electrode defining the inductor 50 andthe linear electrode defining the inductor 60 may be arranged withlongitudinal directions thereof differing from each other.

Second Structure

Next, FIG. 13 is a side surface conceptual diagram showing the mainstructure of a second structure of the duplexer 101. Although, in theexample shown in FIG. 12, the inductor 50 and the inductor 60 areprovided inside the lamination substrate 100, they may be provided notinside the lamination substrate 100 but in the cover layer 290 as shownin FIG. 13. In the structure shown in FIG. 13, the inductor 50 and theinductor 60 include linear electrodes. Then, the mount circuit element420 that provides the inductor 42L and the linear electrode defining theinductor 60 are close to each other. As discussed above, inductivecoupling is able to be generated between the inductor 42L and theinductor 60 as indicated by a thick broken line arrow mark in FIG. 13.

Also in the second structure, the linear electrode defining the inductor50 and the linear electrode defining the inductor 60 are spaced fromeach other in the plane direction. For example, the inductor 60 and theinductor 50 are spaced by the distance therebetween longer than thedistance between the inductor 60 and the inductor 42L. As shown in theside surface conceptual diagram of FIG. 13, the inductor 50 is locatedon one end side of the cover layer 290 while the inductor 60 is locatedon the other end side of the cover layer 290 opposing the one endthereof. With this structure, as discussed above, inductive coupling isnot generated between the inductor 50 and the inductor 60.

Third Structure

Next, FIG. 14 is a top surface conceptual diagram showing the mainstructure of a third structure of the duplexer 101. In the thirdstructure, the inductor 50 and the inductor 60, like the inductor 42L,are each provided by a mount circuit element (for example, a chipinductor) mounted on the top surface 100S of the lamination substrate100. In other words, the inductor 50 and the inductor 60 are eachprovided by a mount circuit element including a housing with arectangular parallelepiped shape or a substantially rectangularparallelepiped shape that includes an insulative material.

As shown in FIG. 14, the inductor 50 is provided by a mount circuitelement 500. The inductor 60 is provided by a mount circuit element 600.Then, the mount circuit element 420 that provides the inductor 42L andthe mount circuit element 600 that provides the inductor 60 are close toeach other.

In the third structure, the mount circuit element 500 that provides theinductor 50 and the mount circuit element 600 that provides the inductor60 are spaced from each other in the plane direction. Note that theplane direction is a direction parallel or substantially parallel to thetop surface 100S of the lamination substrate 100. In FIG. 14, a firstdirection in the plane direction and a second direction in the planedirection are orthogonal or substantially orthogonal to each other. Forexample, the inductor 60 and the inductor 50 are spaced by the distancetherebetween longer than the distance between the inductor 60 and theinductor 42L. The mount circuit element 500 that provides the inductor50 is located at a side, which is positioned on the downstream side ofthe first direction, of the sides of the lamination substrate 100parallel or substantially parallel to the second direction in a planview; the mount circuit element 600 that provides the inductor 60 islocated at a side, which is positioned on the upstream side of the firstdirection, of the sides of the lamination substrate 100 parallel orsubstantially parallel to the second direction.

Strength of the inductive coupling generated between the inductor 60 andthe inductor 42L is able to be adjusted by the distance between themount circuit element 600 and the mount circuit element 420.

Likewise, in order to obstruct electromagnetic field coupling betweenthe inductor 50 and the inductor 60, the mount circuit element 500 andthe mount circuit element 600 are arranged with the longitudinaldirections thereof not opposing each other.

Further, in order to obstruct the electromagnetic field coupling betweenthe inductor 50 and the inductor 60, the center axis of the spiralelectrode in the mount circuit element 500 and the center axis of thespiral electrode in the mount circuit element 600 may be set to beorthogonal or substantially orthogonal to each other.

Fourth Structure

Next, FIG. 15 is a side surface conceptual diagram showing the mainstructure of a fourth structure of the duplexer 101. The fourthstructure differs from the first structure shown in FIG. 12 in a pointthat a linear electrode defining the inductor 50 and a linear electrodedefining the inductor 60 are arranged with an internal ground patterninterposed therebetween inside the lamination substrate 100.

As shown in FIG. 15, the linear electrode defining the inductor 50 iselectrically connected to the internal ground pattern with a viaconductor 52V interposed therebetween. The linear electrode defining theinductor 60 is electrically connected to a base ground pattern differentfrom the internal ground pattern with a via conductor 62V interposedtherebetween. The linear electrode defining the inductor 50 is locatedat a position in the lamination direction relative to the internalground pattern. The linear electrode defining the inductor 60 is locatedat a position on the opposite side in the lamination direction relativeto the internal ground pattern. With this, inductive coupling is notgenerated between the linear electrode defining the inductor 50 and thelinear electrode defining the inductor 60 even if they include anoverlapping portion when the lamination substrate 100 being viewed inthe lamination direction.

The linear electrode defining the inductor 50 and the linear electrodedefining the inductor 60 may be arranged with the internal groundpattern interposed therebetween and to not overlap with each other whenthe lamination substrate 100 being viewed in the lamination direction.With this, inductive coupling between the linear electrodes is furthersignificantly reduced or prevented from being generated. Furthermore, itis sufficient that the inductor 50 and the inductor 60 do not overlapwith each other when the lamination substrate 100 being viewed in thelamination direction, and one of them may be provided in the cover layer290, on the top surface 100S of the lamination substrate 100, or thelike.

Although, in FIG. 15, the inductor 50 and the inductor 60 include theinternal ground pattern interposed therebetween in the laminationdirection, the fourth structure of the duplexer 101 may be in a mode inwhich the internal ground pattern is interposed in the plane direction.

Fifth Structure

Next, FIG. 16 is a side surface conceptual diagram showing the mainstructure of a fifth structure of the duplexer 101. The duplexer 101shown in FIG. 16 is provided with a chip sized package (CSP) structure.

The duplexer 101 includes the filter substrate 200. A filter electrode,a wiring pattern, and the like are provide on the first principalsurface of the filter substrate 200 to provide the transmission signalfilter 20 and the reception signal filter 30 as discussed above.

The duplexer 101 further includes a filter mounting substrate 280. Thefilter mounting substrate 280 includes, for example, an aluminasubstrate, and an area thereof is larger than that of the filtersubstrate 200 by a predetermined amount in a plan view. An electrodewith a predetermined pattern is provided in or on the filter mountingsubstrate 280.

The filter substrate 200 is mounted on a top surface (mounting surface)280S of the filter mounting substrate 280 with bump conductors 281 withthe first principal surface of the filter substrate 200 facing thefilter mounting substrate 280 side. Further, the mount circuit element420 defining the inductor 42L is mounted on the top surface 280S of thefilter mounting substrate 280. On a bottom surface 280R of the filtermounting substrate 280, linear electrodes defining the inductors 50 and60 as well as external connection bump conductors 282 are provided.

The top surface 280S of the filter mounting substrate 280 is coated witha resin layer 283. However, an IDT electrode is not coated with theresin layer 283, and a section of the IDT electrode includes a hollowstructure. With this, the filter electrode and the wiring pattern areable to be significantly reduced or prevented from being exposed to anexternal environment, resonance characteristics of SAW resonators areable to be significantly improved, and the desired characteristics asthe filter are able to be provided with precision.

A spiral electrode defining the inductor 42L and a linear electrodedefining the inductor 60 at least partially overlap with each other in aplan view of the lamination substrate 100. Thus, inductive coupling isable to be generated between the inductor 42L and the inductor 60 asshown in FIG. 16. In particular, in the circuitry and structure of thepresent preferred embodiment, stronger inductive coupling is able to beprovided with ease because an interval (distance) between the spiralelectrode defining the inductor 42L and the linear electrode definingthe inductor 60 are able to be shortened.

Further, as shown in FIG. 16, the linear electrode defining the inductor50 and the linear electrode defining the inductor 60 are spaced fromeach other in the plane direction. For example, the inductor 60 and theinductor 50 are arranged with the distance therebetween longer than thedistance between the inductor 60 and the inductor 42L. As shown in theside surface conceptual diagram of FIG. 16, the inductor 50 is locatedon one end side of the bottom surface 100R of the filter mountingsubstrate 280; the inductor 60 is located on the other end side of thebottom surface 100R of the filter mounting substrate 280 opposing theone end thereof, for example, in a region overlapping with the inductor42L in a plan view of the duplexer 101. This obstructs inductivecoupling between the inductor 50 and the inductor 60.

In addition, the duplexer 101 is able to be compact and thin because thewhole of the duplexer 101 is included in the CSP structure.

In the structures discussed above, although the example in which aninductor is included as a matching circuit is described, a case of thematching circuit being a capacitor is able to be implemented in asimilar structure as well. For example, in place of the mount circuitelement 420 including a spiral electrode, a mount lamination capacitorelement may be included.

Although the above-discussed transmission signal filter 20 is a ladderconnection filter, the transmission signal filter 20 may be, forexample, a longitudinally coupled resonator filter. Also in this case,by adjusting the inductive coupling or capacitive coupling between theabove-discussed matching circuit and inductor, a high frequency modulewith significantly improved isolation characteristics is able to beprovided.

Moreover, the preferred embodiments of the present invention are able tobe applied to high frequency modules by using a bare chip filter.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A high frequency module comprising: a sharedterminal electrically connected to an antenna; a transmission terminal;a reception terminal; a transmission filter electrically connectedbetween the shared terminal and the transmission terminal; a receptionfilter electrically connected between the shared terminal and thereception terminal; and an antenna side matching element electricallyconnected between the shared terminal and a connection portion of thetransmission filter and the reception filter, or a transmission sidematching element electrically connected between the transmissionterminal and the transmission filter; wherein the transmission filterincludes: a plurality of serial arm resonators electrically connected inseries to a serial arm electrically connecting the shared terminal andthe transmission terminal; a plurality of parallel arm resonators eachelectrically connected in series to each of a plurality of parallel armselectrically connecting the serial arm and a ground; a first inductorelectrically connected between the ground and a connection endelectrically connecting at least two parallel arm resonators of theplurality of parallel arm resonators; and a second inductor electricallyconnected between the ground and one parallel arm resonator differentfrom the at least two parallel arm resonators of the plurality ofparallel arm resonators; the second inductor and at least one elementselected from a group including the antenna side matching element, thetransmission side matching element, and a portion of the serial arm inthe transmission filter overlap with each other in a plan view; thefirst inductor and the second inductor do not overlap with each other inthe plan view; and a distance between the first inductor and the secondinductor is longer than a distance between the second inductor and theat least one of the antenna side matching element, the transmission sidematching element, and the portion of the serial arm in the transmissionfilter.
 2. The high frequency module according to claim 1, wherein thehigh frequency module includes the first inductor electromagnetic fieldcoupled to one element selected from the group including the antennaside matching element, the transmission side matching element, and aportion of the serial arm in the transmission filter.
 3. The highfrequency module according to claim 1, further comprising: a receptionside matching element electrically connected between the receptionterminal and the reception filter; wherein the high frequency moduleincludes the first inductor electromagnetic field coupled to at leastone element selected from a group including the antenna side matchingelement, the transmission side matching element, the reception sidematching element, a portion of the serial arm in the transmissionfilter, and a reception path from one end to the other end of thereception filter.
 4. The high frequency module according to claim 1,further comprising: a substrate; wherein the transmission filter ismounted in or on the substrate; and the first inductor and the secondinductor are located at different positions in a plan view of thesubstrate.
 5. The high frequency module according to claim 4, whereinone of the first inductor and the second inductor is a chip inductor ona principal surface of the substrate; and the other one of the firstinductor and the second inductor is inside the substrate.
 6. The highfrequency module according to claim 4, wherein the first inductor andthe second inductor are arranged such that the ground inside thesubstrate is interposed between the first and second inductors.
 7. Thehigh frequency module according to claim 1, wherein the reception filterincludes a series connection terminal, a plurality of serial armresonators, a matching circuit, and a pair of balanced connectionterminals.
 8. The high frequency module according to claim 7, whereinthe plurality of serial arm resonators of the reception filter includesat least one longitudinally coupled serial arm resonator.
 9. The highfrequency module according to claim 1, wherein the ground is locatedbetween the first inductor and the second inductor.
 10. The highfrequency module according to claim 1, wherein the antenna side matchingelement or the transmission side matching element is a third inductor.11. The high frequency module according to claim 10, wherein thedistance between the first inductor and the second inductor is longerthan a distance between the second inductor and the third inductor. 12.The high frequency module according to claim 1, wherein the antenna sidematching element or the transmission side matching element is acapacitor.
 13. The high frequency module according to claim 1, furthercomprising: a lamination substrate; a filter substrate that includes thetransmission filter and the reception filter; and at least one coverlayer.
 14. The high frequency module according to claim 13, wherein thelamination substrate includes a plurality of dielectric layers.
 15. Thehigh frequency module according to claim 13, wherein wiring patterns areprovided on an upper surface of the lamination substrate and externalconnection electrodes are provided on a lower surface of the laminationsubstrate.
 16. The high frequency module according to claim 13, whereinthe filter substrate is a piezoelectric substrate that is mounted on anupper surface of the lamination substrate.
 17. The high frequency moduleaccording to claim 13, wherein the at least one cover layer includes aninsulative material.
 18. A high frequency module comprising: a sharedterminal electrically connected to an antenna; a transmission terminal;a reception terminal; a transmission filter electrically connectedbetween the shared terminal and the transmission terminal; a receptionfilter electrically connected between the shared terminal and thereception terminal; and an antenna side matching element electricallyconnected between the shared terminal and a connection portion of thetransmission filter and the reception filter, or a transmission sidematching element electrically connected between the transmissionterminal and the transmission filter; wherein the transmission filterincludes: a plurality of serial arm resonators electrically connected inseries to a serial arm electrically connecting the shared terminal andthe transmission terminal; a plurality of parallel arm resonators eachelectrically connected in series to each of a plurality of parallel armselectrically connecting the serial arm and a ground; a first inductorelectrically connected between the ground and a connection endelectrically connecting at least two parallel arm resonators of theplurality of parallel arm resonators; and a second inductor electricallyconnected between the ground and one parallel arm resonator differentfrom the at least two parallel arm resonators of the plurality ofparallel arm resonators; the second inductor and at least one elementselected from a group including the antenna side matching element, thetransmission side matching element, and a portion of the serial arm inthe transmission filter overlap with each other in a plan view; thefirst inductor and the second inductor do not overlap with each other inthe plan view; and the ground is located between the first inductor andthe second inductor, or a distance between the first inductor and thesecond inductor is longer than a distance between the second inductorand the at least one of the antenna side matching element, thetransmission side matching element, and the portion of the serial arm inthe transmission filter.